A Case of Canine Oral Melanoma with Similar Histopathological Findings to Human Desmoplastic Melanoma.

Abstract

A 13-year-old, castrated male Labrador retriever was presented with a black, solid and rubbery mass at the right maxillary labial gingiva. Radiography showed that the maxilla was not invaded by the tumor. Histology of a core biopsy specimen suggested a tentative diagnosis of malignant melanoma. A partial maxillectomy including the mass and teeth was performed. Histopathological examination of the surgical specimen revealed a large amount of collagen fibers and neoplastic melanocytes that were quite similar to those of human desmoplastic melanoma. Metastasis to the regional lymph nodes was observed 5 months after surgery and to the lungs 13 months after surgery, when the dog died. To the best of our knowledge, this is the first clinical report on oral desmoplastic melanoma in the dog.